general use test instruments Flashcards
A portable test instrument is used to take real-time (momentary) measurements.
true
A permanent test instrument is a device that is installed in a process, or at a bench, to continually measure and display quantities.
true
AC current is current in a circuit that flows in one direction only.
false
AC voltage is voltage in a circuit that reverses its direction of flow at regular intervals, and is stated and measured as peak, average, or ? value.
rms
The ? value of a sine wave is the maximum instantaneous value of either the positive or negative values in the sine wave.
peak
Voltage indicators only indicate that voltage and current are present; they do not indicate the actual voltage
false
A voltage indicator needs only to be near a voltage source to indicate the presence of voltage.
true
When voltage measurements are different from what is expected, the voltage measurement is most likely to be lower than normal.
true
A(n) ? is a test meter that measures resistance, the opposition to the flow of electrons in a circuit.
ohmmeter
The higher the resistance in a circuit, the higher the current flow through the circuit.
false
A closed switch that is operating properly has continuity.
true
An ohmmeter is used to measure the ?
resistance
When using an ohmmeter, the resistance of all components connected in parallel with the component being tested affects, and typically lowers, the resistance reading.
true
A megohmmeter is a high-resistance ohmmeter used to measure insulation deterioration on various wires by measuring high-resistance values during high voltage test conditions.
trur
? leakage current is current that flows from areas on conductors where insulation has been removed to allow electrical connections.
surface
A clamp-on ammeter is a test instrument that measures current in a circuit by measuring the strength of the ? around a single conductor.
magnetic field
In-line ammeters require the circuit to be ? so the ammeter can be inserted into the circuit to acquire a reading.
opened
A clamp-on ammeter is typically used to measure current in a circuit with over one ampere of current.
true
Measuring current is useful because only current can be used to determine how much a circuit is loaded (working).
true
Many test instruments include a ? in the current-measuring circuit to prevent damage caused by excessive current.
fuse
One problem with small 3-phase voltage imbalances is that they cause high ? imbalances.
current
When a 3-phase current unbalance exceeds ? , a test for voltage unbalance should be performed.
10%
Most analog multimeters do not have calibrated scales that correspond to the different selector switch settings.
false
Most digital multimeter displays include a(n) ? to show changes and trends in a circuit.
bar graph
Voltage measurements using the ? on a digital multimeter are useful in identifying low voltage conditions.
min/max mode
